1. Field of the Invention
The present invention relates to an apparatus for producing a probe carrier by discharging a liquid from a liquid discharging device on a carrier according to discharge data inputted from a host computer or the like, and particularly to a production apparatus of a probe carrier, which is suitable for use in preparation of a DNA microchip or the like by discharging a plurality of probe solutions from a plurality of nozzles provided in a liquid discharging device on a carrier such as a glass substrate and a production process using such an apparatus.
2. Related Background Art
When analysis of a base sequence of a gene DNA, a genetic diagnosis or the like is performed, it is necessary to select a DNA having the intended base sequence using plural kinds of probes. As a means for providing the plural kinds of probes used in this selecting work, there is a DNA microchip called a microarray, probe array, DNA chip or the like. In the DNA microchip, plural kinds of probes are arranged in a state of a two-dimensional array on a solid-phase substrate. About several tens to several thousands of different probes are generally arranged. With respect to a process for preparing this DNA microchip by means of a liquid discharging device, there has been proposed a process in which liquids respectively containing probes are injected and attached on a solid-phase substrate by a liquid discharging device to form spots respectively containing the probes on the solid-phase substrate as disclosed in Japanese Patent Application Laid-Open No. 11-187900.
Since probe solutions are expensive, probe solutions spotted at respective spots on a DNA microchip are generally all different, and the spots are required to be arranged at a high density, the amount of the probe solutions spotted is also controlled to a necessary minimum. For the same reasons, operations consuming a discharged liquid, such as a sucking operation of the discharged liquid and a preliminarily discharging operation, which are generally conducted in ordinary drawing apparatus or recording apparatus, must be avoided as much as possible. However, the sucking operation of the discharged liquid in an ink-jet head using a printing ink is intended to refill the discharged liquid into a nozzle and refresh the discharged liquid in the nozzle. On the other hand, the preliminary discharge is intended to make a discharge condition better. Therefore, when the frequency of these operations is lessened, the discharge condition becomes unstable, resulting in occurrence of problems such as discharge failure.
In the conventional drawing apparatus utilizing a liquid discharging device, methods for avoiding a failure of an image drawn due to discharge failure of the liquid discharging device include methods disclosed in Japanese Patent Application Laid-Open Nos. 06-079956 and 11-000988. The method disclosed in Japanese Patent Application Laid-Open No. 06-079956 is such that an image pattern for specifying non-discharging nozzles is drawn prior to an operation of drawing a desired image, a processing of detecting non-discharging nozzles is performed according to this pattern, and image dots drawn by the non-discharging nozzles are drawn by other substitutive nozzles if the non-discharging nozzles are detected, thereby obtaining the desired image. The method disclosed in Japanese Patent Application Laid-Open No. 11-000988 is such that a processing of detecting non-discharging nozzles is performed in the same manner as described above, and image dots originally drawn by the non-discharging nozzles are supplemented by prolix nozzles not used in an ordinary drawing operation if the non-discharging nozzles are detected.
However, the present inventors have found that when it is attempted to use such a drawing apparatus for printing an image on a recording medium such as paper as described above in preparation of a DNA microchip, expensive probe solutions are wasted more than the preparation needs by the following three reasons, thereby incurring rise in the preparation cost of the DNA microchip.
(1) A discharge failure-detecting pattern for specifying non-discharging nozzles must be drawn.
(2) When a new non-discharging nozzle occurs during drawing of a desired image, the image drawing itself comes to nothing.
(3) Since a high yield cannot be maintained unless discharge is always stabilized, preliminary discharge must be frequently conducted.